{{{ Hugs }}} demon card... i grew up in a family that sounds a lot like yours, and i ran away. when my dad remarried, he did abuse my step-sister, she killed herself. PLEASE get help for your sister~! call Child Protective Services... do not let yourself regret doing nothing for the rest of your life~!
it is hard to feel left out and abandoned even in your grief, i know... my brother and my uncle went to see my mom in the hospital, and i didn't have transportation, they didn't even call me... but now you can process you relationship with your mom without her hurting you.
wishing you the best of a bad time, and all the support you need~!
Gus